72 FRESH-WATER ALG^ OF THE UNITED STATES. 



Remarks. This plant was found in a very stagnant pool, forming, with various 

 other species of alga?, a gelatinous, seruginous-brown stratum, through which the 

 single plants were thickly scattered, without anywhere forming the major portion 

 of the mass. The plants themselves are large enough to be distinguished by the 

 unaided eye. Under the microscope the sheaths are seen to be exceedingly trans- 

 parent and colorless, except in the older part of the filament, where they are often 

 dark brown and opaque ; but even in such case, -the edges are translucent and 

 lighter colored. 



The internal cells or globose masses rarely have distinct coats, and even when 

 such were apparent, as in the older portions of the plants, there appeared to be a 

 communication between the cells. The original main stem is rather short, shorter 

 often than numerous branches into which it breaks up. Very often the apices of 

 the branches are colorless and entirely empty, consisting simply of sheath ; often, 

 however, they are occupied by a cylinder of protoplasm, which is sometimes arti- 

 culated more or les.s distinctly like an oscillatoria. 



Fig. 4, pi. 8, represents a fragment of a filament with a small branch. 



S. lignicola, WOOD. 



S. strato expanse, tomentoso, atro ; trichomatibus ramossissimis, arete intertextis ; ramulis ab- 

 breviatis vel elongatis, subrectis aut varie curvatis, apicibus obtuse rotundatis vcl subacumi- 

 natis ; trichomatum et ramulorum cellulis uni-vel biseriatis, rare in trichomatibus matnris mul- 

 tiseriatis, plerumque pachydermaticis, dilute vel saturate a?rugineis, enormibus, plerumque 

 homogcneis ; cellulis terminalibus in trichomatibus immaturis elongatis, cylindricis, saspius 

 nonnihil oscillatorium rnodo articulatis, granulosis; vaginis sat amplis, haud achrois, vcl 

 luteo-brunneis vel fuscentibus vel ferrugineis. 



Diam. Trich. cum vag. max. r5 Vs" = -OOOC6". 



Syn. S. lignicola, WOOD, Prodromus, Proc. Amcr. Philos. Soc., 18C9, p. 133. 



nab. South Carolina. (Ravenel.) 



Occurring in an expanded, tomentose, black stratum ; filaments very much branched, closely 

 interwoven, branches abbreviate or elongate, nearly straight or variously curved, their apices 

 obtusely rounded or subacuminate ; cells 1-2 seriate, mostly thick-walled, light or deep 

 seruginous, irregular, mostly homogeneous ; terminal cells elongate, cylindrical, frequently 

 articulate somewhat like an oscillatoria, granulate ; sheaths somewhat ample, not transparent, 

 light bright, fuscous or ferruginous. 



Remarks. I have seen dried specimens only of this plant, which were collected 

 by Prof. H. W. Ravenel, in South Carolina. It is said to grow on old boards, 

 and appears to be a very distinct species. There are frequently two or three 

 very short, stubby branches arising together. The apices of the filaments and 

 branches are in some cases filled with endochrome to the end, and are broadly 

 rounded at the apex. In other cases the sheath of the filament extends a distance 

 beyond the endochrome, and is finally rapidly diminished to a point. The cells 

 within the filaments are of various shapes, sometimes globular, sometimes quad- 

 rangular, more often irregular. The original specimens from which this descrip- 

 tion was written were collected in April. I do not know whether they grew 

 immersed, or merely on boards exposed to the weather. I have since received 



